. . . astronomy has shown us that the stars are very far away, and they surround the earth in 3 dimensions, except I continue to experience them as "points of light in the sky." They might as well be glued to an acrylic sphere 20 miles away.

One evening, I looked at the zodiacal light, and rather than being "a cone of light in the sky," it became a mass of dust and gas encircling the sun. Its size frightened me so much that a circuit breaker in my mind blew, and the zodiacal light returned to normal within a second. Even so, I was so shook up that I had to go back inside the house, to the comfort of a human-sized space.

Have any of your readers experienced the Milky Way in 3-d? Did they survive? Did it affect them permanently?

My wife says she can have 3-d flashes at will, when the mood is right. However, in asking around, I gather that such experiences are rare. This points out a dilemma which is common to all science, not just astronomy: little emphasis has been placed on how scientific knowledge can affect our experience of the universe. Instead, the knowledge is packed away in some abstract corner, isn't systematically integrated into our lives, and we remain, in many important respects, medieval peasants, only now we're smart.

The integration process completes a cycle: observe the universe, abstract knowledge from the observations, integrate the knowledge into our experience, observe the universe again . . . only now it's a WHOLE NEW UNIVERSE. This is an exciting point they never told me at the university, since they concentrated exclusively on the first half of the cycle.

But I imagine you Californians have been transforming the universe for some time now. When are you going to do an article on it? Do any of your readers have 3-d flashes? Do they have any ideas about how to have them at will? And how about experiencing fire as an oxidation process?

Gordon Solberg. Rimfire Ranch
Radium Springs, New Mexico

The High Frontier

The one book you must have if you're interested in Space Colonies is this one by Gerard O'Neill. His scheme has aroused so much rabid support and rabid opposition that O'Neill's gentle voice and responsible perspective has a critical balancing influence. I have seen environmentalists who at first blush loathed the idea of Space Colonies come away from O'Neill's book impressed and interested.

Having one individual most strongly identified with a grand vision such as Space Colonies is the healthiest way to proceed, I'm convinced. And I'm glad Gerry has the job on this one.
-SB

When I have considered the effect of our discovering, one day, signals from a more advanced civilization (note that it would be, with almost 100 percent certainty, millennia more advanced than we are because of our own position at the threshold of communication) it has seemed to me overwhelmingly probable that the first effect of the discovery, as soon as the excitement and the novelty have worn off a little, would be to kill our science and our art. What purpose to study the natural sciences? We already know that they are universal, so if a civilization now radioing to us is 50,000 years ahead in its knowledge, why continue to study and search for scientific truth on our own? Gone then the possibility of new discovery, or surprise, and above all of pride and accomplishment; it seems to me horribly likely that as scientists we would become simply television addicts, contributing nothing of our own pain and work and effort to new discovery.

In the arts, music and literature, the case may be somewhat more unclear; yet on earth the almost invariable consequence of contact between a primitive civilization and one more advanced is the stagnation of the arts in the former. Only in the form of a "tourist trade" does art survive, in most cases.

If this sequence of effects is of more than local significance, as I think it is, it will be quite obvious to any civilization more advanced than our own. I would then add one more assumption: that the same characteristics which render a civilization immune to intellectual decay and stagnation, if there be such characteristics, are accompanied by a repugnance to inflict harm on others, in particular to other "emerging" civilizations more primitive than its own. In that case, "They may be out there, but they're kind enough to keep quiet."

Large tugboat driven by reaction engine seen in background has decelerated an asteroid sent in from the main belt and is about to process it from materials
to be used in construction of new space habitats and Earth-orbital solar
powered stations.

I confess to a humanitarian bias in the design that I suggest. Technological revolution is a powerful force for social change, and in choosing among several technical possibilities I have been biased strongly toward those which seem to offer the greatest possibilities for enlarging human options, and for breaking through repressions which might otherwise be unbreakable. Yet I offer no Utopia; man changes only on a time scale of millenia, and he has always within him the capacity for evil as well as for good. Material well-being and freedom of choice do not guarantee happiness, and for some people choice can be threatening, even frightening. Though I acknowledge that my study will be of the physical environment, and only indirectly with the psychological, I will still try to describe an environment which combines with its efficiencies and its practicality opportunities for increasing the options, the pleasures, and the freedoms of individual human beings.

I have argued that there is only one way in which we can develop truly high-growth-rate industry, able to continue the course of its development for a very long time without environmental damage: to combine unlimited solar power, the virtually unlimited resources of the Moon and the asteroid belt, and locations near Earth but not on a planetary surface.

Much the best source of news on Space Colony matters, the L-5 News is an enthusiastic publication of admirable vigor, and it's no fanzine. The editors and contributors are in the thick of Space Colony design and speculation. They plan to live in Space.

L-5 News
L-5 Society
1620 N.Park Ave
Tucson, AZ 85719

-SB

WHAT ARE LIBRATION POINTS?
T. A. Heppenheimer

Our organization name is the L-5 Society, and our newsletter has stated that L-5 is one of the libration points in the Earth-Moon system. But what are libration points? The answer is that libration points are locations where a spacecraft may be placed so as always to remain in the same Position with respect to the Earth and the Moon.

Suppose the Earth and Moon were fixed in space and did not move. Then a single libration point would exist at the point where the gravity fields of Earth and Moon cancel out. A body placed there would feel equal and opposite attractions from Earth and Moon, and so would stay fixed in place. But if the body were moved slightly, it would feel a slightly greater attraction from either Earth or Moon, and so would fall down, moving rapidly away from the libration point. That point, therefore, is unstable.

In reality, the Earth and Moon are in motion about their center of mass. (It is the Moon, of course, which does most of the moving.) This means that, in addition to the gravity of Earth and Moon, we must take account of the centrifugal force acting on a body in orbit. Libration points are then the points where these three effects cancel out: the two gravity fields, and the centrifugal force.

The French mathematician, Lagrange, in 1772, showed that there are five such points. Three of them lie on a line connecting the Earth and Moon. These are L-1, L-2, and L-3. They are unstable; a body placed there and moved slightly will tend to move away, though it will not usually crash directly onto the Earth or Moon. The other two are L-4 and L-5. They lie at equal distance from Earth and Moon, in the Moon's orbit, thus forming equilateral triangles with Earth and Moon. These Points are stable. It is a curious fact that they are stable because the Moon is only 0.01215 times the total mass of Earth and Moon together. If the Moon were greater than 0.03852 times the total mass, L-4 and L-5 would be unstable.

The situation, however, is even more complex than this. The Sun is in the picture, and it disturbs the orbits of spacecraft and colonies. It turns out (from an extremely messy calculation done only in 1968) that with the Sun in the picture, a colony should be placed not directly at L-4 or L-5, but rather in an orbit around one of these points. The orbit keeps the colony about 90,000 miles from its central libration point. The orbit is roughly bean- or kidney-shaped. It may seem curious to speak of an orbit about a point. Actually, the colony is in orbit about the Earth, but the simplest way to describe the orbit is from the point of view of an observer sitting always at the libration point.

In the colonization project, the colonies are to be located in the vicinity of L-4 or L-5. L-2, located behind the Moon, is the site of a catcher vehicle, which collects mass shot up from the Moon by the mass-driver. L-1, between the Earth and Moon, is the location of a satellite power station, to provide power for the moon base. No use has yet been found for L-3. However, at L-3 the Moon is permanently eclipsed by the Earth, so it could serve as an asylum for people suffering from lycanthropy (werewolf tendencies).

VAPOR DEPOSITION OF MASSIVE STRUCTURES

Work done this summer suggests the possibility of fabricating space structures directly from vaporized metals. If proven out by further design work and by vacuum chamber experiments, it promises to provide a textbook example of the use of space conditions in processing, and may cut the cost of a colonization program by some tens of billions of dollars.

Fabrication of seamless hulls or hull segments would be a simple and useful application. The solar energy flux, vacuum, and lack of gravity in space make it easy to vaporize metal and direct it as a conical beam: metal plate of the desired strength and thickness can then be built up on a balloonlike form made of plastic film.

This technology seems applicable to both aluminum and steel alloys, to structures many kilometers in diameter, and to structures more complex than smooth balls. Because it requires little equipment and negligible labor, it promises to reduce the cost of some space structures to little more than the cost of raw material. It seems a fruitful area for further research.

Eric Drexler

A recent study at the Hudson Institute entitled The Next 200 Years in Space (NASA Bicentennial Planning) by Herman Kahn and William M. Brown, predicts the building of space communities and manufacturing facilities.

This is a public lobby set up by Werner von Braun shortly before he died to help build a broad Space constituency and help keep Washington informed
of what that constituency wants. Apparently it's pretty effective and is riding adroitly the burgeoning new public interest in Space. Good newsletter!